User:Nicolas17/MobileMail/MessageViewController/previewActionForSwipeAction:withMessage:forSwipe:

This method is actually called -[MessageViewController _previewActionForSwipeAction:withMessage:forSwipe], but underscores cannot be used in wiki page names.

-(UIPreviewAction*)_previewActionForSwipeAction:(unsigned long long)action withMessage:(id)message forSwipe:(BOOL)swipe;

This method in MessageViewController creates a UIPreviewAction object (action shown in the 3D Touch "peek" view). It's called by leadingPreviewAction and trailingPreviewAction to get the actions on the sides of the peek, and by _previewActionsForSwipeActions:excludingSwipeActions: for the actions at the bottom.

This method contains two jump tables (at least in arm64), presumably compiled from switch statements, which Hopper doesn't handle automatically even in the disassembly, and it's a bit of a pain to figure them out manually.